Variations in color on the surface of a leaf enhance the interest of any plant. Among bromeliads, some of the most desirable species have a particular form of color variation where the leaves feature cross-bands of contrasting color. In addition to their inherent beauty, a closer look reveals some interesting, and unexpected, details.

There are three distinctly different forms of cross-banding seen in the cultivated bromeliads. The most common form is that seen in Aechmea chantinii. The white bands on this species are formed by the heads of tightly packed peltate trichomes. The band-forming trichomes have a cap composed of rings of empty cells. In Aechmea chantinii, these empty cells stick above the leaf surface, but this is not the case in some other species. Walls of the empty cells scatter light very efficiently in all wavelengths, especially when dry, so they appear white. Contrasting bands are formed by areas of the leaf where the trichomes are widely separated from each other, allowing the color of the leaf blade to show.

There is an apparently unlimited number of banding patterns among the cultivated forms of Aechmea chantinii. In almost all cases, the bands stretch across the entire width of the leaf or nearly so but these bands may be straight or jagged in appearance. They may be present on both sides of the leaf, or only on the underside of the leaf. The white bands do not necessarily have the same width. In cultivated clones there is a tendency to select plants with even band widths, but in other clones, especially among the earlier clones collected in the wild, it was very common to have bands of greatly different width next to each other. In other wild collected types, for example, Aechmea chantinii 'Tarapoto' from Tropiflora, the white bands are considerably wider than the green bands of normal leaf color. There are also great variations in the contrast between the color of the white bands and the bands of normal leaf color. When the light-scattering trichomes are densely packed, the bands completely obscure the color of the underlying leaf. When they are less tightly packed, the leaf color shows through to a greater or lesser extent.

Many other species are found scattered through out the Bromeliaceae with white bands formed in the same way. Among the Aechmea species we have: Aechmeazebrina, a very close relative of Aechmea chantinii. Three closely related species: Aechmea fasciata, Aechmea flavorosea and Aechmea caesia, have bands formed the same way, but the bands are not so regular in appearance and usually do not span the entire width of the leaf blade. The most widely grown cultivars of Aechmea fasciata in the current market favor...